An MDC Partners shareholder pushing for a board shakeup has gone public with its dissatisfaction with the holding company, which is currently searching for a new CEO and exploring a possible sale.

In an SEC filing Wednesday afternoon, FrontFour Capital which says it owns 5.1 percent of the holding company revealed that it had initiated private conversations with MDC’s board in August to replace CEO Scott Kauffman “with a candidate better suited to leverage the strength” of its agencies and to grow its market share in certain industries. According to the filing, “shortly thereafter, the board hastily announced Mr. Kauffman’s intention to resign as CEO by December 31, 2018 without having commenced a search for his replacement, and then announced the launch of a strategic review process a week later.”

The filing says that FrontFour has “stressed the importance of shareholder representation” on the board to better align its perspectives with that of MDC’s shareholders “particularly at this critical juncture.” FrontFour claims MDC’s board has rejected its requests.